Download Mendels Laws of Genetics

the study of patterns of
inheritance and variations
in organisms.
GENES: control each
trait of living thing by
controlling the
FORMATION of an
organisms PROTEINS.
 Chromosomes are DIPLOID
(A PAIR OF
CHROMOSOMES) therefore,
each cell contains TWO
GENES for each TRAIT.
▪One from MOM
▪One from DAD
 Genes may be the SAME or they
could be DIFFERENT
▪Produce DIFFERENT
CHARACTERISTICS of each
TRAIT
▪EXAMPLE: gene for plant height
might occur in TALL or SHORT form.
▪Different forms of a gene
are called ALLELES
▪The TWO ALLELES are
SEGREGATED during
GAMETE FORMATION
(MEIOSIS II)
▪Dominant allele: allele that
is EXPRESSED
▪Recessive allele: allele that
is ONLY EXPRESSED when
there is no dominant allele
present.
Modern Genetics: Based
on GREGOR MENDEL’S
explanations for the
patterns of HEREDITY in
garden PEA PLANTS.
▪CROSSING different PEA PLANTS
▪Crossing: to mate or BREED two
INDIVIDUALS
Pea plant with PURPLE FLOWERS
with a type that has WHITE
FLOWERS.
ALL OFFSPRING HAD PURPLE
FLOWERS
Mendel CROSSED those
OFFSPRING and produced some
WHITE FLOWERS and some
PURPLE FLOWERS.
 (THE WHITE FLOWERS CAME BACK!)
1. Every trait (like flower color, or
seed shape, or seed color) is
controlled by two "heritable
factors". [We know now that
these are genes - we each have
two copies of every gene].
2. If the two alleles differ, one
is dominant and one is
recessive. Dominant traits
mask the appearance of
recessive traits.
3. Alleles are randomly donated from
parents to offspring - the factors
(alleles) separate when the gametes
are formed by meiosis, allowing all
possible combinations of factors to
occur in the gametes.
a.EXAMPLE: if a person has attached earlobes, the phenotype is “attached earlobes” if a p
3. Gene Composition is known as
GENOTYPE
 The expression of the genes is
PHENOTYPE
 EXAMPLE: if a person has attached
earlobes, the phenotype is “attached
earlobes” if a person has free earlobes, the
persons PHENOTYPE IS FREE EARLOBES
a.EXAMPLE: if a person has attached earlobes, the phenotype is “attached earlobes” if a p
▪It’s was you SEE
a.EXAMPLE: if a person has attached earlobes, the phenotype is “attached earlobes” if a p
b. two paired ALLELES in
an organism’s
genotype may be
IDENTICAL,
HOMOZYGOUS.
a.EXAMPLE: if a person has attached earlobes, the phenotype is “attached earlobes” if a p
c. The two paired ALLELES in
an organism can also be
DIFFERENT,
HETEROZYGOUS.
▪DOMINANT trait is
EXPRESSED
a.EXAMPLE: if a person has attached earlobes, the phenotype is “attached earlobes” if a p
Mendel’s Law of
DOMINANCE: When an
organism has TWO
DIFFERENT ALLELES for a
trait, ONE ALLELE IS
DOMINANT.
a.EXAMPLE: if a person has attached earlobes, the phenotype is “attached earlobes” if a p
Mendel’s Law of
SEGREGATION: During
GAMETE formation by a
DIPLOID organism, the pair of
ALLELES for a trait SEPARATE,
during MEIOSIS.
 Mendel’s Law of INDEPENDENT
ASSORTMENT: The members of
a GENE PAIR SEPARATE from
one another INDEPENDENTLY
from the members of the other
GENE PAIRs.
NAME MENDELS 3 LAWS OF GENETICS
 1.
 2.
 3.
5. Using a PUNNETT SQUARE: to
PREDICT the PROBABLE GENETIC
COMBINATIONS in the OFFSPRING
that result from different PARENTAL
ALLELE COBINATIONS that are
INDEPENDENTLY assorted.
 MONOHYBRID CROSS examines the
inheritance of ONE TRAIT.
▪ HOMOZYGOUS-HOMOZYGOUS
▪HETEROZYGOUS-HETEROZYGOUS
▪HETEROZYGOUS-HOMOZYGOUS
▪HETEROZYGOUS-HOMOZYGOUS
 EXAMPLE: trait for height
▪ T= DOMINANT TALL
▪ t= RECESSIVE SHORT
 The suare shows the following
GENOTYPES:
 PARENTS ARE THE F1 GENERATION
resulting in offspring as F2
GENERATION
The square shows the following
GENOTYPES:
 1:4 RATIO of__________________ ____%
 1:4 RATIO of__________________ ____%
 2:4 RATIO of__________________ ____%

The square shows the following
PHENOTYPES:
 3:4 RATIO of__________________ ____%
 1:4 RATIO of__________________ ____%

a PEDIGREE is a family
history that shows HOW A
TRAIT is INHERITED over
several GENERATIONS.
a.
can help answer questions
about THREE aspects of
inheritance
1. SEX LINKAGE
2. DOMINANCE
3. HETEROZYGOSITY
b. males have ONE X AND
ONE Y CHROMOSOME.
PROCESS OF REPLACING
SPECIFIC GENES IN AN
ORGANISM IN ORDER TO
ENSURE THAT THE
ORGANISM EXPRESSES A
DESIRED TRAIT.
1. CLONING:
an IDENTICAL copy of a gene or an entire organism is produced.
a. Take specific genes from
ONE ORGANISM and
place them INTO
ANOTHER ORGANISM.
1. CLONING: an IDENTICAL copy of a
gene or an entire organism is
produced.
scientists INSERT a normal gene
into an ABSENT OR
ABNORMAL GENE. Once
inserted the normal gene begins
to produce CORRECT proteins or
enzymes. This ELIMINATES the
cause of the disorder
3. Results of genetic engineering
may include:
a. the development of PLANTS that
make their own INSECTICIDES.
b. the development of ANIMALS
that are BIGGER, FASTER,
RESISTANT TO DISEASE.
9. SELECTIVE BREEDING:
method of artificially
SELECTING and BREEDING
only organisms with a DESIRED
TRAIT to produce the next
generation.
a. inbreeding: CROSSING
INDIVIDUALS THAT ARE
CLOSELY RELATED.
1. NOT THE BEST
OPTION: DISEASE
DEVELOPS EASILY.
b. HYBRIDIZATION: choosing
and breeding organisms that
show STRONG EXPRESSION
for TWO DIFFERENT TRAITS in
order to produce their offspring
that express the desired traits.